In wireless broadband systems, for example, a wireless metropolitan area network (WMAN) may be based on IEEE 802.16e, 2005 standard, also know in the art as WiMAX. The WMAN may include a plurality of base stations and plurality of mobile stations. A mobile station may perform a hand-over from one base station to another base station. The mobile station may roam from one wireless communication network to another wireless communication system. Roaming may be done from a first base station of a first wireless communication network to a second base station of a second wireless communication network. In WMAN, when the mobile station performs the hand over, some processes and/or security measures may operate on transmissions between the mobile station and the base stations. The hand over may be seamless to the mobile station. The security measures may include decryption/encryption and authentication of the transmissions.
During hand over from a source base station to a target base station, an authentication key (AK) for the target BS may be derived, prior to the hand over, while the mobile station is connected to the source base station. Thus, the mobile station may perform the hand over without the need to perform full authentication.
The mechanism of deriving AK automatically from a parent key, e.g., a pairwise master key (PMK), may generate a context per derived key. The context may be derived only once per base station and PMK, and may be used until the PMK expires. Thus, the mobile station and/or the base station may need to cache the AKs and context being used to later be re-used when the mobile station is handed over to a previously used base station.
It will be appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements.